Cable Query

Recently got a car cam but the power cable is too short to be routed along the edge of the windscreen so being the clever chap that I am got a 2mtr lead with a male usb plug at one end and female micro usb plug at the other end which would go direct into the camera. This was attached to a female micro usb/female usb adaptor so the original power lead would fit but just one slight problem..................it didn't work, the camera icon showed it was getting no power.Bit puzzled as to why it did not work as logically, at least to me it should have worked.Any ideas on the above or any cheap alternative solutions.Garmin do a 5mtr lead but that's a bit pricy at £21.95